Platorchestia smithi, Lowry, 2012

Lowry, J. K., 2012, Talitrid amphipods from ocean beaches along the New South Wales coast of Australia (Amphipoda, Talitridae), Zootaxa 3575, pp. 1-26 : 14-19

Platorchestia smithi sp. nov.

( Figs 8–10)

Types. Holotype, 7.9 mm, AM P.85703, Brooms Head Beach , New South Wales (29.61145°S 153.33557°E), under algae (present for about two weeks) in the supralittoral zone at south end of beach near the headland, J.K. Lowry, J. Dermand & K. Engelberg, 8 February 2010, NSW 3658 . Paratypes: female, AM P.85704, same station data as holotype .

Material examined. New South Wales. 5 males, 29 females and juveniles (only 1 ovigerous female), AM P.88063, Shelley Beach at Ballina, New South Wales (28.86613°S 153.59212°E), very flat, beach, talitrids at back of beach under woody debris and Pandanus leaves, J.K. Lowry, J. Dermand & K. Engelberg, 6 February 2010, NSW 3656; 3 males, 99 females and juveniles (less than 5 ovigerous females), AM P.88064, Broadwater Beach, Broadwater National Forest, New South Wales (29.03237°S 153.45595°E), very flat, beach with talitrids under light vegetated debris, 5 m high dunes at back of beach leading into dense vegetation, J.K. Lowry, J. Dermand & K. Engelberg, 6 February 2010, NSW 3655; 69 males, 251 females /juveniles, AM P.88065, Spooky Beach, Angourie, New South Wales (29.47958°S 153.35937°E), wide, very flat beach, bordering on vegetated boulder shelf, talitrids under pieces of dried algae, sticks and Pandanus fronds at back of beach, J.K. Lowry, J. Dermand & K. Engelberg, 5 February 2010, NSW 3654; many specimens including 20+ males, AM P.88066, Brooms Head Beach, New South Wales (29.61145°S 153.33557°E), under algae (present for about two weeks) in the supralittoral zone at south end of beach near the headland, J.K. Lowry, J. Dermand & K. Engelberg, 8 February 2010, NSW 3658; 15 males, 48 females and juveniles (3 ovigerous females), AM P.88067, Back Beach at Brooms Head, New South Wales (29.61662°S 153.33597°E), sandstone fingers emerging from vegetated dunes at back of beach, talitrids living at back of beach under light vegetative debris where freshwater seeps from dunes, J.K. Lowry, J. Dermand & K. Engelberg, 8 February 2010, NSW 3657; 7 males, 48 females and juveniles, AM P.88068, Minnie Waters, New South Wales (29.76937°S 153.29471°E), supra-littoral, flat beach with main population of talitrids at back of beach where fresh water was seeping onto beach. Found less commonly under pieces of the brown alga Hormosira banksii, J.K. Lowry, J. Dermand & K. Engelberg , 5 February 2010, NSW 3652; many specimens, AM P.88069, Wooli, New South Wales (29.87671°S 153.26378°E), under accumulated Zostera on sandy substrate at back of mangroves; J.K. Lowry, J. Dermand & K. Engelberg, 5 February 2010, NSW 3653; 5 males, 12 females /juveniles, AM P.88070, Little Beach at Red Rock, New South Wales, Australia (29.98272°S 153.23140°E), supra-littoral, flat broad beach with nearly vertical cliff faces at back of beach, talitrids sheltering under woody debris, Eucalyptus leaves, Casuarina needles, J.K. Lowry, J. Dermand & K. Engelberg, 5 February 2010, NSW 3651; 61 males, 210 females /juveniles (20 ovigerous), AM P.88071, Arrawarra Beach, New South Wales (30.06129°S 153.19977°E), supralittoral zone, flat beach, huge accumulation of the brown kelp, Ecklonia at south end of beach near headland, present for about two days, talitrids living up the beach under dryer algae, J.K. Lowry, J. Dermand & K. Engelberg, 9 February 2010, NSW 3659; 14 males, 69 females /juveniles (11 ovigerous), AM P.88072, Woolgoolga Beach, New South Wales (30.11119°S 153.20235°E), supralittoral zone, flat beach, gently sloping vegetated dune merging into top of beach, talitrids living under light algal debris at south end of beach near headland, J.K. Lowry, J. Dermand & K. Engelberg, 9 February 2010, NSW 3660; many specimens, 8+ males, AM P.88073, Moonee Beach, New South Wales (30.21464°S 153.16106°E), rocky cove with a lot of woody debris, talitrids living under woody debris in supralittoral zone, J.K. Lowry, J. Dermand & K. Engelberg, 9 February 2010, NSW 3661; 18 males, about 49 females /juveniles (5 ovigerous females), AM P.88074, Nambucca Heads, New South Wales (30.64939°S 153.01122°E), marine/brackish water pond separated from estuary by rocky training wall, talitrids living under heavy layer of Zostera and Casuarina needles, J.K. Lowry, J. Dermand & K. Engelberg, 10 February 2010, NSW 3663; 8 males, about 80 females /juveniles, including 4 ovigerous females, AM P.88075, Scotts Head Beach, New South Wales (30.74589°S 152.99184°E), supralittoral, very flat beach beach, talitrids found under woody debris in small depression just before vegetated dunes near south end of beach near headland, J.K. Lowry, J. Dermand & K. Engelberg, 11 February 2010, NSW 3664; 8 males, about 63 females /juveniles (none ovigerous), AM P.88076, Grassy Head Beach, New South Wales (30.79499°S 152.99788°E), supralittoral, flat beach beach, small population found under light woody debris at south end of beach near headland, J.K. Lowry, J. Dermand & K. Engelberg, 11 February 2010, NSW 3665; 16 males, about 31 females /juveniles (13 ovigerous), AM P.88080, Oxley Beach, Port Macquarie, New South Wales (31.43433°S 152.92207°E), small, flat beach with headlands north and south, talitrids living in supralittoral under woody and grassy debris at south end of beach just below grassy covered hillside, none found under washed up Ecklonia, J.K. Lowry, J. Dermand & K. Engelberg , 12 February 2010, NSW 3667; many specimens, AM P.87702, landward edge of rock platform between Bateau Bay beach and Crackneck Lookout from sand under leaf litter and wrack at landward edge of Avicennia mangroves (33.3889°S 151.4842°E), S. Keable, R. Keable, 5 September 2011; many specimens, AM P.88077, Tarum Road, North Avoca Beach, New South Wales (33.45891°S 151.43981°E), dry stream bed running onto beach behind rock platform, talitrids common among wrack in stream bed, well above high water, wrack mainly small sticks and pieces of leaves, J.K. Lowry, 28 March 2010, NSW 3673; many specimens, AM P.88078, McMasters Beach, New South Wales (~ 33°29'57.55''S 151°25'29.00''E), flat sandy beach with almost no wrack, some dried Ecklonia , near the southern headland there is a storm water drain at the back of the beach with talitrids living here under large stones among accumulated sticks and leaves, J.K. Lowry, 28 March 2010, NSW 3674; 6 specimens, AM P.87947, Maitland Bay, New South Wales (33°31.512'S 151°23.780'E), L. Fanini & J.K. Lowry, November 2011; 217 specimens, AM P.85970, north end of Putty Beach, Bouddi National Park, Central Coast, New South Wales, Australia (33°31.715'S 151°22.445'E), upper supralittoral under patches of dead Zostera, J.K. Lowry & I. White , 22 April, 2011, MI NSW 3686 (stn 3); 16 males, 53 females and juveniles (12 females ovigerous), AM P.88079, Pearl Beach, New South Wales (33.54786°S 151.30737°E), at the absolute southern end of the beach there are talitrids living under small patches of dried brown algae in a depressed moist area at the back of the beach where the forest begins, J.K. Lowry, 28 March 2010, NSW 3675; 66 specimens, AM P. 87948, Portuguese Bay, New South Wales (33°36.656'S 151°18.096'E), L. Fanini & J.K. Lowry, November 2011; 1 male, 11 mm, AM P.85953 (illustrated), female, xx mm, AM P.85954 (illustrated), 9 specimens, AM P.85952, Palm Beach ferry wharf, Pittwater, New South Wales, Australia (33°35.756'S 151°19.194'E), on sand under beach wrack, J.K. Lowry and R. Peart; many specimens, AM P.85951, east of Spit Bridge, Middle Harbour, New South Wales, Australia (33°48'12"S 151°14'45"E), under rocks and woody debris, 29 August 2002, S. Keable, NSW 1965; 7 specimens, AM P.88081, Bellambi Beach, just north of boat ramp, New South Wales (34°22'13"S 150°55'35"E), sand under leaf litter and wrack at landward edge of Avicennia mangroves, J.K. Lowry & A. Bopiah, 28 April 2010; 18 males, 76 females and juveniles, AM P.84394, mouth of Minnamurra River, New South Wales (34°37'41"S 150°51'27"E), sound and gravel beach, A.D. Murray & S.J. Keable, 6 May 2010, NSW 3979, many specimens, AM P.84394, south end of Minnamurra River entrance, west of boat ramp, New South Wales (34°37'41"S 150°51'27"E), A. Hegedus, 6 May 2010; many specimens, AM P.84006, north end of Jones Beach, Kiama Downs, New South Wales (34°38'9"S 150°51'23"E), R. T. Springthorpe, 6 May 2010; 63 specimens, AM P.86727, southern end of Washerwoman's Beach near rocks, New South Wales (35°14'40"S 150°32'9"E), A. Hegedus, 25 August 2011; 127 specimens, AM P.86720, 79 specimens, AM P.86721, north end of Bendalong Beach near rocks, New South Wales (35°14'40"S 150°32'10"E), A. Hegedus, 23 August 2011.

Type locality. Brooms Head Beach , New South Wales, Australia (29.61145°S 153.33557°E), under algae in the supralittoral zone at south end of beach near the headland .

Description. Based on holotype, male, 7.9 mm, AM P.85703.

Head. Eye medium (1/5–1/3 head length). Antenna 1 short, rarely longer than article 4 of antenna 2 peduncle. Antenna 2 more than half body length; peduncular articles incrassate (expanded); article 5 subequal than article 4; peduncular articles with many small robust setae. Lower lip with vestigial inner plates. Mandible left lacinia mobilis 5-dentate. Maxilliped palp article 2 distomedial lobe well developed, 4 reduced, button-shaped.

Pereon. Gnathopod 1 sexually dimorphic; subchelate; coxa smaller than coxa 2, subtriangular, about as broad as deep; posterior margin of carpus and propodus each with lobe covered in palmate setae; propodus subrectangular, anterior margin with 3 groups of robust setae, lateral surface with 3 cuspidate setae, posterolateral surface with 6 serrate setae, posteromedial surface with 4 serrate setae; palm transverse, with 7 serrate setae; dactylus subequal in length to palm. Gnathopod 2 sexually dimorphic; subchelate; coxa similar in size to coxa 3, broader than deep; basis slightly expanded; ischium without posterodistal lobe on medial surface; posterior margin of merus, carpus and propodus each without with lobe covered in palmate setae; carpus triangular, reduced (enclosed by merus and propodus), posterior lobe absent, not projecting between merus and propodus; propodus 2.5 × as long as wide; palm acute, reaching 30% along posterior margin, with small sinus midway, lined with robust setae, without protuberance near dactylar hinge, with small midpalmar sinus, posterodistal corner with groove; posteromedial surface of propodus with groove; with cuticular patch at corner of palm; dactylus subequal in length to palm, not attenuated distally. Pereopods 2–4 coxae as wide as deep. Pereopods 3–7 cuspidactylate. Pereopods 3–7 dactyli without distal patch of many rows of tiny setae on the anterior margin. Pereopod 4 significantly shorter than pereopod 3; carpus significantly shorter than carpus of pereopod 3; dactylus similar to that of pereopod 3. Pereopod 5 propodus distinctly longer than carpus. Pereopod 6 shorter than pereopod 7; coxa posterior lobe posteroventral corner rounded, posterior margin perpendicular to ventral margin, posterior lobe with ridge, posterior lobe with 3–4 marginal setae. Pereopod 7 basis lateral sulcus present, slightly pronounced, posterodistal lobe present, rounded, produced downwards almost to merus; distal articles (merus and carpus) slender; merus posterior margin evenly rounded.

Pleon. Pleopods all well developed. Pleopod 1 peduncle with marginal robust setae; biramous, outer ramus shorter than peduncle. Pleopod 2 biramous, outer ramus shorter than peduncle. Pleopod 3 biramous, outer ramus shorter than peduncle. Epimeron 2 longer than epimeron 3 (slightly). Epimeron 3 posterior margin minutely serrate, with 7 or 8 setae, posteroventral corner with small subacute tooth, ventral margin without robust setae. Uropod 1 not sexually dimorphic, peduncle with 11 robust setae, peduncle distolateral robust seta absent; inner ramus subequal in length to outer ramus, with 3 marginal robust setae; outer ramus without marginal robust setae. Uropod 2 not sexually dimorphic; peduncle with 4 robust setae; inner ramus subequal in length to outer ramus, with 1 marginal robust setae; outer ramus with 1 marginal robust setae. Uropod 3 peduncle with 3 robust setae; ramus longer than peduncle, ramus linear (narrowing), ramus with 2 marginal robust setae, ramus with more than 5 apical setae. Telson as broad as long, apically incised, dorsal midline entire, with marginal and apical robust setae, with 3–6 robust setae per lobe.

Female (sexually dimorphic characters). Based on paratype, female, AM P.85704. Antenna 2 peduncular articles slender. Gnathopod 1 parachelate; posterior margin of merus, carpus and propodus each without lobe covered in palmate setae. Gnathopod 2 mitten-shaped; basis strongly expanded; posterior margin of carpus and propodus each with lobe covered in palmate setae; carpus well developed (not enclosed by merus and propodus), posterior lobe present, projecting between merus and propodus; palm obtuse, smooth, not lined with robust setae; without cuticular patch at corner of palm.

Habitat. Under beach wrack on sand.

Remarks. Platorchestia smithi is the common wide-spread beach-hopper along New South Wales ocean beaches. It belongs to the Platorchestia (group 2) complex with incrassate male second antennae and no sexual dimorphism in pereopods 6 or 7. These species are all similar. Platorchestia smithi is most similar to P. monodi in the shape of the male gnathopod 2 propodus palm, both of which have a weak proximal palmar sinus. Platorchestia smithi differs from P. monodi in having a relatively long propodus in relation to its width (2.5 ×) on male gnathopod 2 (1.3 × in P. monodi ) and in the basis of pereopod 7 which is significantly longer (1.5 ×) than broad (about as long broad in P. monodi ).

Distribution. New South Wales: ocean beaches and bays from Shelley Beach at Ballina (29°S) to Bendalong Beach (35°S).